Burner with tangential air admission and restricted throat



April 2,1957 J. woLFERsPl-:RGER 2,787,318

BURNER WITH TANGENTIAL AIR ADMISSION AND RESTRICTED `Tl-IROAT Filed Nov. 4, 1949 2 Sheets-Sheet l J. J. WOLFERSPERGER BURNER WITH TANGENTIAL. AIR ADMISSION April '2, 1957 AND RESTRICTED THROAT Flled Nov. 4, 1949 v 2 Sheets-Sheet 2 Arm Mw@ (ttorneg s BURNER WITH TANGENTIAL AIR ADMISSION AND RESTRICTED THROAT `lohn J. Wolfersperger, Milwaukee, `Wis. Application November 4, 1949, Serial N o. 125,582

9 Claims. (Cl. 15S-1.5)

This invention relates to a burner with tangential air admission and restricted throat.

The present application is a companion to my application Ser. No. 636,781, entitled Pressure Type Burner and Method of Burning Fuel, and filed December 22, 1945, now Patent No. 2,499,207, dated February 28, 1950. An object of the present invention is to reduce the space required for a burner of the type disclosed in my companion application above identified and to promote the rapidity of combustion while protecting metal parts from unduly high temperatures.

It is a further and important object of the invention to produce a hotter ame than is achieved in the device of my companion application, or inV any comparable burner.

Further objects of the invention include a reduction in cost of manufacture; a simpliiication in the burnerl structure; an improved air control for eliminating carbon deposits; and an improved means for adding large quantities of diluting air to the products of combustion without interfering with complete combustion.

Fig. 1 is a view in axial section through an improved burner embodying the `present invention as the burner appears when installed in-a boiler. Y

Fig. 2 is an enlarged axial section-al view through the mixing chamber of my improved burner., y

' Fig. 3 is a view in transverse section on the line 3 3 of Fig. 2.

Fig. 4 is a`detail -viewin perspective of` one of the air transferring conduits used in the device of Figs. l to 3.

Fig. l5 is a view partially in side elevation and partially in vertical, axial section showing my improved burner installed in an upright boiler.

Fig. 6 is a View inaxial section showing a modified embodiment of my burner as it appears when used as a torch.

Fig. 7 is a view taken in cross section on the line 7-7 of Fig. 6.

' Fig. 8 is a View 'taken in cross section on the line 8-8 of Fig. 6.

The boiler 10 comprises a generally cylindrical side wall and convex heads 11 and 12 with water inlet at 13 and water or steam outlets at 14. Within the boiler shell is a helical fire tube 15 having an inlet portion 16 forreceiving gases from the multiple chamber burner hereinafter to be described,` the` opposite endof the helix-having a ue opening at17 through the head 11 for the discharge of products of. combustion.

I Mounted in the head 11 is a tubular mixing chamber 20 flanged at 21 to receive the end plate 22.-- At the inner end of the tubular mixing chamber `2 0 is a conical partition wall 23 terminating in the restricted-orifice 24 which communicates with aY combustionchamber'ZS having the form of Ian elongated vtubeofY largecrosssection closed at 26 in its remote end and communicating laterally with the inlet 16 of lire tube 15.AY annular closure27at the lefthand end of suchtube as viewed in Figs. 1 and 2, is

nited States Patent O 2,787,318 r Patented Apr. 2, 1957 TCC welded or otherwise secured to the conical member 23 about the restricted orifice 24. The combustion chamber 25 is desirably subdivided into a number of separate compartments by frusto-conical partitions or baflies 28 and 29, each of which provides restricted communication between the successive compartments. The frusto-conical baflies are desirably spaced at intervals of one to two diameters of the combustion chamber 25 wherein they are mounted. Their use is made practical by the fact that the combustion chamber tube 25 is immersed in the water of Ithe boiler and hence delivers heat sutciently ,rapidly into the water to carry oif from the baies the heat which would otherwise destroy them. The bailies are desirably welded throughout their peripheries to the tube 25 to promote heat delivery from the bales to the tube 25 and thence to the water of the boiler.

Within the mixing chamber sleeve 20 is a baffle sleeve 30 having its end portion 31 in immediate proximity to the frusto-conically tapered terminal wall 23 which partitions the mixing chamber from the combustion chamber. The baille sleeve 30 may be supported by brackets 32 (Fig. 2) or otherwise. Centrally within the sleeve 30 is the fuel atomizing nozzle 33 supplied with fuel through pipe 34 from the fuel pump 35 which is driven by the armature shaft 36 of motor 37. Immediately adjacent the nozzle tip is the igniter 38 which may be of any suitable type.

Opening tangentially at 4l) into the chamber 20 is the air supply pipe 41 leading from a blower 42 aligned with, and driven by, the armature shaft 36. A large body of :air delivered tangentially into chamber 20 creates a vortex in such chamber.

The fittings 44 which are conveniently mounted on the end wall or closure plate 22 of chamber 20, and one of which is separately illustrated in Fig. 4, comprise baille means desirably in the form of conduits having inlet openings 45 in the path of a whirling mass of air which is confined between the tubular outer wall of chamber 20 and the exterior surface of the tubular baffle sleeve 30 therein. Thus each of the inlet openings 45 constitutes a scoop tthrough which air is caused to enter the tting 44, issuing from the outlet opening 46 thereof in a direction which is axial of sleeve 30. In practice, I iind it desirable to transfer in this manner to the interior of sleeve 30 about onesixth of the air admitted to chamber 20 through the tangential inlet opening 40.

In previous burner designs, there has tended to be a :surplus of air moving through the baffle sleeve 30 past the nozzle. Thus it was necessary to somewhat restrict the flow and, in order to rectify or straighten the flow, a considerable space has had to be provided between the nozzle and the end wall of the mixing chamber. In the present device there would be, but for the scoops or deflectors 44, a deficiency of air within 'the tubular baffle. Therefore, the scoops or their equivalent are needed to provide adequate primary air about the nozzle. Such primary air should be barely sufficient to support stable combustion, but, as disclosed in the companion application above identified, should not be more than the amount necessary for this purpose. I have found that these scoops constitute an extremely simple means of supplying exactly the. right amount of air and sutileiently rectifying its ilow axially of the sleeve so that the nozzle can be mounted directly on the closure plate 22 as shown. This reduces the overall length of the burner very materially below what has previously been deemed necessary. Yet no carbon or tar deposits occur.

It will be noted that the ltangential inlet port is suoiently large so that a substantial part of the air admitted therethrough is blown against the side of the bailie sleeve 30, which lies across the path of such air and is cooled thereby.

3 The method of operation is the same as that described in the companion application aboveide'r'itie'd, but im# portant advantages are realized in the present burner.

The forward or axial velocity of the spiralling air in.

chamber 20 is necessarilythe saine for a given burner eapacity'as in tthe'previous device' (the same amountof air being requiredV to be delivered for complete combustion) but the very muchlong'er path which is necessarily followed by air flowing' spirally, requires the actual velocity of the a'ir to be greatlyin'excess of the velocity it would have if it were moving solely in an axial direction. Consequently, when lthe high velocity secondary air encounters the frusto-'c'onical wall 23 and moves toward the restricted orifice 24, Veven greaterturbulence results than'was achieved by that orifice without the tangential flow,

Secondly, it being an object of the invention disclosed in my former application, as well as the present device, to' keep the secondary airseparate from ythe mixture of fuel and primary air which has been ignited at the burner, until .sudden and turbulent mixing occurs att the orifice, itfpis found that the rapid vortex movement of the relatively colder secondary air assists in maintaining the secondary air in the form of an annular stratum outside of the' slowly burning mixture. v

Inthe third place, the considerations above noted pro duce at the orifice a flame which is between 500 and 1000 F. hotter than that previously achieved, even in the burner of my companion application, wherein the flame produced was exceptionally hot.

Inl :the fourth place, the superior mixing achieved in the throatas a result of the considerations noted makes it possible to increase the diameter of the throat or orifice 24 as compared with a throat or orifice used in the straight tlow burner of the companion application, this, in turn, permitting a reduction in air pressure to only one-third or one-fourth that required in the straight llow burner at any specified rating.

Finally, the use of the scoop fittings 44 not only permits the entire mixing chamber to be shortened, as above noted, but eliminates baffles and the like while securing improved 'results.

Apart from those lchanges and improvements in the mixing'chambe'r, furtheradvantages are achieved by the baflles 28 and 29 in the combustion chamber which, by abruptly varyingv the rate of flow of thegases,` promote turbulence and heat exchange.

The device of Fig. 5 is closely comparable to that already described but the water jacket 100 is vertical with its yinlet pipe 130 extending downwardly from its top and its outlet pipe 140 opening from its top. The mixing chamber tube 200 is set into the side wall of the'boiler. Internally, its organization is the same as thatalready described, its tangential inlet being shown at 400. In this construction, the first compartment of the combustionchamber comprises an extension 201 of the mixing chamber tube, the tapered wall 230 being merely a baille in such tube. The combustion chamber tube 250 constitutes a lateral extension upwardly from the compartment 20T and it is provided with a series of conical baffles 280, 290 and 291. The fire tube may be identical with that already described. The operation is essentially the'same as that already described.

In the device shown in Figs. 6, 7 and 8, a modified arrangement is desirable because, unlike those previously shown, Ithe combustion chamber is not immersed in boiler water and therefore its walls and bales require protection from the intense heat. At the same time, in many installations, suchjas forage crop driers, it is important `to reduce the temperature of the products of combustion where the hot gases are usedin contact with the material being dried. In other devices, such as gravel driers and the like, it is immaterial whether 'products of combustion rare reduced in temperature since their contact with the gravel or other work will do no harm.

The device of Fig. 6 resembles that of Fig. 5 to the extent that the tube 202 which constitutes the wall of the mixing chamber is extended at 203 to provide a cornbustion chamber 252. The frusto-conical baille 232 provides a restricted orifice 242 between the mixing chamber and the combustion chamber. A similar frustoconical bafile at 282 providesy a restricted orifice 243 through which the hot gases enter into a drum 50 wherein is contained the material to be dried, whatever that material may be.

As in the constructions.previously disclosed, there is a baille sleeve 30 within the mixing chamber, and thc fuel nozzle 33 is mounted near the back end of sleeve 30. The nozzle 33Y and` igniter 38 are conveniently mounted directly' on the closure plate 22. Such plate also carries the scoop fittings 44 which pick up the air moving spirally in chamber 202 and convey such air centrally and release it axiallyofl sleeve 30 to provide primary air for the fuel issuing from nozzle 33.

The air is admitted tangentially to chamber 202 through the opening 40fwhich opensfrom the pipe 410. Instead of coming directly from the blower or other air pump, however, the pipe 410i`s vdesirably merely a branch of the pressurefpipe 411, another branch 412 of which leads to a tangential opening at 400 into the combustion chamber 252 externally ofthe frusto-conical baille 232. Each of the branch lpipes. 410and `412U is desirably controlled by a damper 53, 54 so that the airmay be divided in any desired proportions between the tangential inlet port 40 of the mixingy chamber and the tangential inlet port 400 of the combustion chamber..

By suitable regulation of the dampers, any desired operation of the burner. within its capacity may be achieved. Where maximum temperatures are desired, and where thesupply of air available 4vgreatly exceeds that needed for complete combustion the r .dampers may both be closed to such an extent that the total air admitted through bothk ofthem will not substantially exceed the amount required for complete combustion. This air may be divided in equal quantities between thetwo tangential inlet ports, or as low as 1/3 through the first inlet port. In either case, for reasons .above lnoted, the tangential ow o f the air cooperates with the abruptly restricted orifice to produce an intensely hotlflame. In my former burner, I have found that where the air supplied is approximately the exact amount needed for completecombustion, the length, of the flame extending from the burner will approximately. equal the overall length of the,

burner. With such a. bur ner mounted on the headrof a drier drum, this resultsfinthe flame projecting for a considerable distancey into the drum. The present device with its two chambersissubstantially identical in length as the former burner, but, by .reasonlof -thetangential inlets and two chambers, combustion is practically completed in the second, chamber and practically Vno flame protrudes from its outlet throat. Thus no flame will extend therefrom intoar rlryi ng drurn, so that a shorter drum may be used, or the same drum could dry more material.v

However, alargereduction in the temperatureof the products of combustion ymaybe, achieved by supplying excess air. For 'this purpose,` the dampers 53- and 54 may be opened 4beyondI the requirements for complete combustion to supply-.air whichwill dilute the products of. combustion andpartakeof their heat so that the gases delivered into the tiryingcharnbei; 50 will be greatly increased in volume,butdcorrespondingly `reduced vin temperature. This Ais pta-1,'.tic 1 1l ar ly desirable for the drying of edible produce end brewery grains and thelike by direct contactwith-the gases. I have A.found that due to the spiral flow resultingfromthe tangentially disposed inlets, it isjpossible to introduce up to 300%:excess of air into the mixing chamber and another 300%; excess into the combustionfchamber over and above the air re quired for complete combustion, without in any way inter'fenng with the achievement of complete combustion, free VLof soot `or tar. ,Thus the flow of gasescanbe multiplied six-fold.

A very important advantage of the admission of air through the tangential oriiice 400 consists in the cooling of the truste-conical baie or partition 232 which provides the restricted opening 242 whereby mixing and combustion are abruptly perfected. It will be remembered that in the devices originally disclosed, this frusto-conical wall was immersed in the water of a boiler, whereby its excess heat could be carried oli directly into the water. I have found the admission of air around its external face to be an important factor in keeping this bale at a reasonable operating range of temperatureswhere it is deprived of contact with the liquid. The tangential inlet at 400 also maintains a'stratied body of cooler air around the entire inner surface of the combustion chamber 252, thereby protecting the combustion chamber wall and baille 282 from excessive heat.

I claim:

1. A burner comprising the combination with a fuel nozzle, of a tubular chamber wall substan-tially concentric therewith and having a tangential air inlet, a sleeve spaced Within such wall and encircling the nozzle, and a restricted throat comprising a conically tapered and centrally apertured terminal wall for said chamber spaced from the sleeve at the end of the chamber toward which said nozzle is directed, the aperture being materially smaller in cross section than the sleeve, the other end of the chamber being provided with a closure behind the nozzle, the said sleeve having an inlet opening within said chamber and adjacent said closure for the admission from the outer part of said chamber of primary air for the fuel from said nozzle, said closure comprising a plate upon which the nozzle is supported and from which the end of said sleeve is spaced, said plate being provided with bai'e means having a generally radial extent and having air scoop means to deflect into the interior of the sleeve, air moving in a vortex resulting from its tangential delivery into the space between the sleeve and the chamber wall.

2. A device of the character described comprising the combination with a generally cylindrical tubular chamber wall having a rear closure plate atone end and a restricted throat comprising a frusto-conically tapered wall with a central aperture at its other end, the tubular chamber wall having a tangentially disposed inlet, a nozzle mounted on the closure plate Iand directed centrally of said tubular` chamber wall toward the aperture `of the frusto-conically tapered wall, and a sleeve of larger diameter than said aperture 4and spaced from the closure plate and encircling the nozzle between the nozzle and the tubular chamber wall and terminating short of the frustoconically tapered wall, said sleeve Ibeing disposed across a substantial portion of the cross sectional area of the tangential inlet port aforesaid whereby air admitted therethrough to the space between the sleeve and the tubular chamber Wall is directed in substantial part against the side of the sleeve, in further combination with conduit means mounted on the closure plate and having laterally disposed inlet ports in the path of air encircling the sleeve, and axially disposed 4outlet ports 4between the sleeve and the nozzle.

,3. A burner of the character described comprising a tubular chamber Wall having a tangential inlet, Va nozzle disposed substantially axially of the wall, a closure across the end of the wall behind the nozzle, and at least one deflector tting mounted on the closure and comprising an air scoop disposed adjacent said wall in a position to deflect toward the nozzle air circulated by said tangential inlet about the inner periphery of the wall, said iitting having a tangential inlet and a delivery portion directed axially from said closure along the axis of said tubular wall for delivery of primary air axially about the nozzle.

.4. Axburner of the character described comprising the` i, constituting restricted throats at the outlets of the respec-` tive chambers, the aperture of the wall of the first of said chambers opening centrally into the next of said chambers and the respective chambers 'being provided solely at their respective ends remote from their respective walls aforesaid with tangential air inlet ports, a fuel nozzle in the lirst of said chambers, a sleeve within the first chamber and spaced from its terminal wall and encircling the fuel nozzle between the nozzle and the inlet port of said first chamber, said sleeve being larger in diameter than the opening in the throat at the end of its chamber, said nozzle 'being materially spaced from the throat end of the sleeve, means for supplying air under pressure to the respective ports to establish correspondingly rotating vortex currents of air in said chambers, and a closure for the first chamber behind said nozzle and in spaced relation to said sleeve, said closure ybeing provided with delector means having radial extent for guiding toward said nozzle primary air from the air admitted externally of said sleeve by the tangential port opening into said first chamber. v

5. A method of burning fuel and controlling the temperature of the products of `combustion of said burning, comprising the steps of injecting the fuel into a stre-am of primary air suiii-cient only to support stable com'bustion igniting the mixture of primary air and fuel, surrounding the stream of ignited primary air and fuel with a stratified envelope of helically rotating secondary `air yat least approximately sufficient to complete combustion when added to said stream, combining said stream and envelope for the first time by abruptly passing said stream and envelope simultaneously through a restricted throat of smaller cross section than the stream of primary air, adding a stratied envelope of cooling air about the ignited mixture, and passing the ignited mixture and the envelope of cooling air through a second restricted throat.

6. The method of claim 5 in which said stream is circular and the secondary air and cooling air are admitted tangentially to be mixed with said burning -fuel on a whirling path.

7. The method of claim 5 in which the supply of secondary air and cooling air lare relatively adjustable.

8. A burner comprising the combination with a fuel nozzle, of a tubular cham-ber wall substantially concentric therewith and having a tangential air inlet, Ia sleeve spaced within said wall and encircling the nozzle, a portion of said sleeve being opposite said inlet to deflect incoming air on a helical path of secondary air between said sleeve and said wall, an igniter adjacent said nozzle, means for supplying said nozzle with primary air within said sleeve, said sleeve having axial extent beyond said nozzle sufiicient to maintain said primary air within said sleeve separate and in stratified relation to the helical path of secondary air outside said sleeve at least until said sleeve is substantially filled with an ignited mixture of fuel and primary `air in stable combustion, a restricted throat comprising a conically tapered and centrally apertured terminal wall for said chamber spaced from the sleeve at the end of the chamber toward which said nozzle is directed, the aperture Ibeing smaller in cross sectional area than the sleeve, said sleeve and restricted throat comprising means for iirst contacting the helically rotating secondary air with the ignited mixture of fuel and primary air just prior to violent intermixture thereof while abruptly withdrawing bot'h secondary and primary air from the chamber through said restricted throat, said tubular chamber comprising a mixing chamber, and a combustion chamber with which said mixing chamber communicates, said restricted throat comprising a partition `between said chambers, the combustion chamber having an air inlet adjacent th'epartition.to-supply additional i airto 4the combustionrclramber andfrthefinlettto saidecom'bustion chamlberlbeing tan'gential'iny theA same direction as thetangential inlet tothemixingchamber torinducc vortex movement-in the-same direction in both chambers, said inlet comprising a branch of the .inlet to the mixing chamber, in Vfurther combination Vwith damper means for regulating the relative ow 'throughsaidinleta 9. Thevdevice` fclaim` 8 in which the port opening tangentially intothe `combustion chamber is disposed outside of the 'frusto-conically tapered wall of the mixing chamber outletl to direct cooling-air about the external surfacey of said wall.

8 Scott Apr. 6,V Austin Y Apr.- 26, Elze et al. Oct. 21; Good. Oct. 29, Nagel July 2, Kerrick June 2,r Wood' Dec. 8, Hanson et al. Feb. 6, Carter Dec. 23, Arnhym July 20, Raskin Oct. 25, Wol-ferspergery Feb. 28, Lelgemannl Mar. 14, Logan et-al July 18,

FOREIGN f PATENTS- Great Britain Apr. 5, 

